1. Field of the Invention
The present invention generally relates to hand-held labelling and marking devices for printing information such as prices, etc. on a label material, or alternately, directly onto an article. Such devices are currently used in most stores, but especially large numbers of such units are used in supermarkets. Such devices for labelling and marking will typically have a printing mechanism with a number of print wheels or printing belts for carrying the print-type. In the case where print wheels are used, the print wheels can preferably Be coaxially mounted in the printing mechanism, whereas, when belts are used, the belts are guided around multiple, coaxial sets of guide wheels within the printing mechanism. These guide wheels can include printing area-side guide wheels for positioning the print-type that is to be printed, and oppositely spaced adjustable guide wheels for rotatably positioning the belts to a desired print-type at a printing location about the printing-area side guide wheels.
More specifically, the present invention relates to a printing mechanism, preferably for a hand-held labelling unit, and the housing of the printing mechanism. In general, the housing surrounds and holds the belts or wheel printing mechanisms and also an axially movable control shaft for adjusting individual ones of the belt strips or wheels. The housing can preferably be formed by two housing parts, which housing parts can be divided along a plane which is parallel to the plane of a belt or wheel.
2. Background Information
The units as described above are typically used to mark retail merchandise, by applying a marking directly onto the individual products or packages, or by marking an adhesive label and then applying the adhesive label to the packages or products, to indicate at least the selling price. Because the prices are different from product to product, the printing mechanism must of course be adjustable, at least to some extent, if the printing mechanism is to be used universally. One possibility for adjustment of such a printing mechanism is to equip the unit with an axially movable control shaft. Such a control shaft can preferably be extracted in steps, to make it possible to individually adjust each of the individual belts or wheel printing mechanisms.
But there are also applications in which objects must be labelled with serial numbers. Consequently, such a printing mechanism should also be able, if necessary, to print not always the same group of symbols, but other symbols or groups of symbols, instead of or in addition to the original symbols, e.g. numbers in an ascending series. This requirement that it be possible to individually set known printing mechanisms for serial numbering, etc., requires that the printing mechanism be equipped with an advancing mechanism that advances the print-type at least one printing unit for every label or marking produced.
In a labelling unit, in particular a hand-held labelling unit of the type described above, a number of labels can be located on a feeder roll, and the labels can be printed in sequence by means of the printing mechanism. A corresponding dispenser, incorporated into the labelling unit can deliver the printed labels to the products or to their packaging. The labels are transported through this labelling unit by means of a corresponding stepper mechanism, and at the appropriate time, the printing mechanism can be moved toward the label to print the label. Various printing processes can be used, but essentially, this process is comparable to stamping a document. For reasons of weight alone, efforts can generally be made to keep units or the components of such units as small and lightweight as possible. In addition, so that a hand-held labelling unit is still easy to pick up and operate, attention must of course also be paid to small size and light weight. On a belt or wheel printing mechanism, for example, there can be a limit to the size or number of symbols which dan be located on each wheel. The general objective, however, is to reduce the size and weight of the unit end of its components.
On one type of known wheel printing mechanism, the housing consists of a base part, which base part contains practically the entire mechanism, and a cover. The cover is by and large flat, and closes the base part. Both parts of the housing must be detachably connected to one another for purposes of assembly, and also for repair. For this known printing mechanism, this detachable connection is made by means of screws, the geometric axes of which extend parallel to the axes of the wheel printing mechanism. Each screw requires a threaded hole, and on this known unit, this requirement for providing a threaded hole typically results in a significant increase in the size of the housing, in relation to the size which would be required only to hold the wheels themselves.